The word "streetsweeper" a slang term used to describe any fully/semi automatic shotgun, but mainly the DAO-12. The "streetsweeper" is a popular choice for drive-by shootings, which is where it's name comes from.

Not all the vehicle's is long enough to stash the streetsweeper
-Lloyd Banks

Contrary to popular belief, a "street-sweeper" is not just a large-capacity compact shotgun; the term also includes most automatic compact firearms as well (Ex: Uzi, MAC-10, Ak-47, etc). The term "street-sweeper" was given to these weapons because they are capable of spraying an alley or narrow street in one "sweep" (usually without even releasing the trigger or changing clips).

"...and if it's major,
hit me on my pager,
I'll load up the creeper,
and pop a clip into this Street Sweeper!"